desperately need reliable search

I use OpenOffice to create zillions of word processor files with the extension .odt
Finder and/or Spotlight finds words usually, but not always, and this is not acceptable!
I need to search everywhere in the computer for single-word strings like "Duncan" or "reincarnation" and I've done numerous tests that prove words are not being seen inside of files.
I installed EasyFind, but it doesn't find everything either.
I read up on a couple of other search programs, they're talking about how they do currency conversions or send email or wash the floors, or whatever - I don't care about any of that -
Also, I read a number of instructions that are supposed to find words through the Terminal but none of them seems to work either.
My feeling is, it can't be because they're .odt files, because I AM able to find things most of the time - but it's not dependable and I need dependable.
As a professional writer, I need a search that will infallibly find single words in my files.
PLEASE HELP!

Check your Spotlight prefs to make sure nothing is excluded in the Privacy Tab.

It is also possible that your Spotlight index is corrupted. Try rebuilding it:

1. Open the Spotlight preferences and go to the Privacy tab. Click on the + button and add Macintosh HD (if that is the name of your drive) to the Privacy Tab.
2. Close the System Prefs.
3. Re-open the Spotlight prefs and use the minus button to remove MacIntosh HD from the privacy list.
4. Close System Prefs.

I guess the "problem" with ODF-files is that regardless of their suffixes (ODT, ODS, ODP etc), all ODF files are just ZIP archives. Inside them, the actual content is always stored in one plain text file called, unsurprisingly, content.xml. So in order to find something the system first has to decompress these files before they can be searched. I don't know if Spotlight does that for ODF-files.

A second search of Stack Exchange, limited to Ask Different, found http://apple.stackexchange.com/a/122586/8546 with a belief that DEVONthink "builds its own search index, not relying on Spotlight". I'll test DEVONthink Pro Office (on Sierra) and edit the answer. Done.

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